Descriptive Problem Summary: In the map editor, using Find and Replace to replace a full tile turf with a partial tile turf, doesn’t work in some instances with using Replace (not Replace All).

Numbered Steps to Reproduce Problem:
1) Download the following test project: http://files.byondhome.com/Higoten/Tests/ Replace%20Undo%20issue.zip
2) Navigate to map.dmm.
3) Use Find and Replace to replace /turf/Test2 with /turf/Test3 using the Replace feature (Do not use Replace All).
4) Observe that the black /turf/Test2 has not been replaced with the blue /turf/Test3.

Expected Results: For turfs to be replaced using the Replace feature.

Actual Results: Turfs are not replaced using the Replace feature.

Does the problem occur:
Every time? Or how often? Every time.

When does the problem NOT occur? The issue does not occur when using Replace All.